Researchers have developed a simple, cost-effective test to classify BRAF V600E–mutant colorectal cancer (CRC), advancing personalized therapy. The new immunohistochemistry (IHC)–based system, called iBM, uses two protein markers—CD8, indicating immune activity, and ARHGEF17, involved in cell-cycle regulation—to identify tumor subtypes without expensive genomic sequencing.
The test categorizes tumors into two groups: iBM1, with high immune infiltration, and iBM2, driven by cell-cycle and metabolic activity. This classification matches traditional genomic profiling in over 70% of cases. Clinically, iBM1 tumors respond well to immune checkpoint inhibitors (64% response rate), while iBM2 tumors show high sensitivity to BRAF plus EGFR inhibitors (80% response rate). Among untreated patients, iBM2 tumors were linked to longer overall survival (29 vs. 20 months for iBM1).
By translating complex genomic data into routine pathology, the iBM system enables cost-efficient, precision-guided treatment for this aggressive CRC subtype. Researchers note that larger studies are needed to validate the approach for widespread clinical use.